1. Field of Invention
This invention relates to a window stay.
2. Discussion of the Background
There is a move internationally toward projected side hung windows. That is windows where the sash is mounted with the window frame via stays at the side or top and bottom such that when the window opens the sash projects from the frame. Such construction provide for tall window sashes which can be conveniently opened for ventilation and which enables the exterior surface of the glass to be cleaned by gaining access thereto by reaching around the "hinge" side of the fully opened sash.
Improved access for cleaning is achieved by opening the window sash up to 90.degree.. This has traditionally been achieved by the use of friction stays which incorporate a sliding shoe component. However, a drawback with such stays is that the sliding shoe tends to jam up at 90.degree. opening due to the geometry of the stay in conjunction with the operation of the sliding shoe in a dirty environment. The latter is especially so in a casement window with the stay mounted on the window sill.
The development of sealed friction bearings has resulted in window stays able to effectively operate in such dirty environments.
With a move toward wider window sashes (for example 600mm to 900mm wide) the strength requirements for window stays able to support and control such sashes have increased. The increased strength characteristics can be achieved by increasing the thickness of the stay components and more particularly the arm(s). While this can sometimes lead to difficulties accommodating this stay in the cavity between the sash and frame, the overriding concern can be the rise in manufacturing costs and hence cost to the end user. Therefore there is an opportunity to provide a window stay which is able to carry wider sashes yet is economical to manufacture.
There is also a problem with wind gust causing wide sashes to be slammed open or closed, leading to destruction of the stays and/or the sash and glass. To overcome this the friction level in the bearings can be increased. However, the friction level required to prevent a sash moving in a wind gust of say 20 m/s (45 mph) the resistance to movement is such that the sash cannot be readily moved by a person in order to open or close the sash. There is thus a need for a window stay which can be used to support a sash so that it will not move in the wind, yet can be easy to move by hand which results in an obvious conundrum as achieving one criteria generally leads to an inability to achieve the other.